Nosie in long exposure shots

Discussion in 'Photography Beginners' Forum' started by sapper6fd, Sep 17, 2010.

  1. sapper6fd

    sapper6fd TPF Noob!

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    Hello all,

    I have a question to pose to all the experienced people here.

    I went out to shoot a few images last night and to just play around with my D90 at night. I noticed a lot of noise in the shots and am wondering what may be causing it.

    The images were shot at 200 ISO, f11 with a shutter speed of 25 seconds. Now for my question. When using a slow shutter speed at 200 ISO, is there an expectation that the noise will increase in the image due to the length of exposure? I tried pumping up the ISO 640 and decreasing the shutter speed, noticed a slight decrease in the noise, but not by much.
     
  2. bigtwinky

    bigtwinky No longer a newbie, moving up!

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    Long exposures can result in more noise.

    Try turning out the function "long exposure noise reduction". Typically found in advanced settings of your camera. Thats what its called in my Canon, not sure about Nikon.
     
  3. sapper6fd

    sapper6fd TPF Noob!

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    I've got that same feature in my D90, I used it on one photo but ended up waiting around a minute for it to do its thing on the photo before it would let me take another. I'll give that another go though,
     
  4. bigtwinky

    bigtwinky No longer a newbie, moving up!

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    I've seen that the amount of time it takes for the in camera noise reduction is about the same as the shutter speed.
    25s photo = 50s wait time

    You could also rely on noise reduction in post processing
    Or you could up the ISO somewhat if your camera can handle clean higher ISO
     
  5. Josh66

    Josh66 Been spending a lot of time on here!

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    Yes. The reason is that the way it works is that it takes a second exposure of the same length as the first one (but this second exposure is dark - the shutter curtains are closed), and then it subtracts anything that shows up on the second one.

    Useful to get rid of noise, only drawback is that you'll be limited on how soon you can do a follow-up shot.

    IMO, long exposure noise is better than high ISO noise... Plus, some things (e.g. - star trails) can only be done with long exposure.
     
  6. KmH

    KmH Helping photographers learn to fish Supporting Member

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    Because it's a different kind of noise.

    High ISO noise is amplifier induced noise while long exposure noise is temperature noise.

    Not only do they look different, the way they are addressed in the camera or during post processing is also different.
     
  7. Derrel

    Derrel Mr. Rain Cloud

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    It is called AMP noise...and is unfortunately pretty common on long exposures made with d-slr cameras.
     
  8. Gaerek

    Gaerek TPF Noob!

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    Some of the best star trails shots I've seen were taken with multiple relatively short (~30 second) shots merged in post. The act of merging will still give you your star trails, but the random noise will cancel out after the merge.
     
  9. LittleMike

    LittleMike No longer a newbie, moving up!

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    I found that out the hard way. After a 27 minute exposure :confused:
     
  10. Gaerek

    Gaerek TPF Noob!

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    LOL

    This made me chuckle. How was it not using your camera for an hour?
     
  11. IgsEMT

    IgsEMT No longer a newbie, moving up!

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    Its time to go back to film :) I miss the flavor of NPH
     
  12. LittleMike

    LittleMike No longer a newbie, moving up!

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    Luckily I was pretty sure I nailed the picture on the first try, so I just drove 45 minutes back home and worried the whole time :lol:
     

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